1. Field of the Invention
This invention relates to a thermoplastic olefin elastomer (hereinafter abbreviated as TPO) molded article. More particularly it relates to a TPO molded article which has a sealant contact portion coming into contact with a urethane sealant and which consists substantially of a TPO material.
The present application is based on Japanese Patent Application No. Hei. 11-76595, which is incorporated herein by reference.
2. Description of the Related Art
The present invention will be described with particular reference to a molding 26 used at the periphery of an automobile windowpane as shown in FIG. 1 (hereinafter simply referred to as a molding) for instance, but the invention is not limited thereto and is applicable to other moldings having a sealant contact portion, such as a roof molding 27 shown in FIG. 4 and a sealant dam 20 shown in FIG. 1.
A window shield (windowpane) 12 is fitted into a window frame 14 formed by sheet metal working as follows. The window frame 14 is made up of a flange 16 forming the bottom (the car interior side) and an upright wall 24.
A sealant 22 is fitted to the flange 16. A window shield 12 having a sealant dam 20 adhered to the periphery thereof via a both-sided adhesive tape 18 is fitted into the frame 14 and pressed toward the car interior to press down the sealant 22, whereby the window shield 12 is fixed to the flame 14. Then a molding 26 is fitted into the space surrounded by the window shield 12 and the upright wall 24.
The molding 26 basically comprises a main body 28 that is on the exterior side, a leg 30 that extends from the main body 28 toward the interior, and a sealant contact portion 32 that is provided at the tip of the leg 30. The main body 28 has sealing lips 34 and 36 by which it hooks on to the exterior periphery of the windowpane 12 and the exterior periphery of the frame 14, respectively. The sealant contact portion 32 has a lip 38 by which it hooks on to the interior periphery of the windowpane 12 and a lip 40 in friction contact with the upright wall 24 of the flame 14.
The molding 26 has been produced by extruding polyvinyl chloride (hereinafter abbreviated as PVC), etc., cutting the profile, setting cut pieces of the profile in a mold, and making the corners by injection molding to obtain an annular molding.
A urethane sealant is generally used as the sealant 22 for its adhesion to glass, vibration damping properties, durability, and sealing properties. Since the sealant 22 and the molding 26 should have strong heat-resistant adhesion, the surface 32a of the sealant contact portion 32 of the PVC molding 26 which is to come into contact with the sealant 22 is usually coated with an isocyanate primer to secure adhesiveness.
From the viewpoint of environmental conservation and resources saving, it has been demanded to replace PVC with other molding materials. Hence the inventors have focused their study on TPO which has the lowest density in thermoplastic elastomers and made efforts in development. They have found, however, that a urethane sealant fails to have sufficient adhesion to TPO for practical use, particularly adhesive strength after a heat test. A primer that secures adhesion between a urethane sealant and TPO has not yet been developed.